On Sun, Oct 24, 2010 at 2:50 AM, Martijn van Oosterhout <klep...@svana.org> wrote: > Can we please not get MERGE hung up on trying to make it atomic. The > standard requires no such thing and there are plenty of uses of MERGE > that don't involve high concurrency updates of the same row by > different processes. If we want an atomic UPSERT, make that a seperate > command, MERGE without atomicity is useful enough already.
Really? I don't really see any point in a non-atomic MERGE. Nor in a non-atomic UPDATE or INSERT or any other operation. The A in ACID is as important as any other letter. For that matter if you don't care about atomicity then this is a problem already solvable easily solvable in the application. Why bother providing a special command for it. The whole reason to want a special command is precisely because the database can implement it atomically more easily and more efficiently than any application implementation. Moreover having a case which is non-atomic and allows inconsistent results or errors in the face of concurrent updates is a foot-gun. Someone will come along and try to use it and it will appear to work in their application but introduce nasty hidden race conditions. -- greg -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
